Phototransduction

Question 1

What happens in the absence of light?

Answer 1

1. Photo receptors turned on
2. Cells become depolarised and glutamate produced.
3. This turns bipolar cells off in the centre and on in the off centre

Question 2

What happens in the presence of light?

Answer 2

1. Photon hits rhodopsin
2. Retinal becomes cis from all trans which alters opsin and starts a casculation cascade
3. Phosphodiesterase is activated which closes CGMP channels and stops glutamate production
4. Bipolar turned on in centre and off in off centre
5. Optic nerve activated